1. Field of the Invention
The present invention relates to a thin film magnetic head device to be used with a magnetic recording and reproducing system, more particularly, to a thin film magnetic head device to be used with a magnetic recording and reproducing system which conforms to a plurality of recording formats having different in numbers of channels and track widths, in which the magnetic tape as a recording medium runs forward and backward, and the relative positions between the magnetic tape and the magnetic head are substantially fixed.
2. Description of Prior Art
FIG. 4 is a view of a conventional thin film magnetic head to be used with a magnetic recording and reproducing system in which the magnetic tape runs forward and backward and which conforms to a plurality of recording formats having different numbers of channels and track widths. FIG. 4 shows the case of a combination type thin film magnetic head 36 made by combining two thin film magnetic heads conforming to the recording format of one-side having 4 channels and one-side having 2 channels.
On a substrate 20 there are formed the reproducing transducers 21a, 21b, 21c and 21d which are constituted by the thin films for four channels, and the reproducing transducers 22a and 22b which are similarly constituted by the thin films for two channels, and on a substrate 30 there are formed the recording transducers 31a, 31b, 31c and 31d which are constituted by the thin films for four channels, and the recording transducers 32a and 32b which are similarly constituted by the thin films for two channels.
As a reproducing transducer, there is formed a magneto-resistive type transducer made by applying the well known magneto-resistive effect of a magnetic thin film or a coil type constituted by winding a thin film coil around a thin film magnetic core. As a recording transducer, there is formed the well known inductive type transducer similarly made by winding a thin film coil around a thin film magnetic core. The track width Tr of the recording transducer is formed to agree with the track width of the corresponding format.
On the substrates 20 and 30 there are constituted a thin film magnetic head for reproducing 25 and a thin film magnetic head for recording 35 with the cover plates 23 and 33 being bonded thereto, respectively. With respect to the thin film magnetic head for reproducing 25 and the thin film magnetic head for recording 35, the substrates are mutually bonded and a combination type thin film magnetic head 36 is constituted.
Other methods of combining the thin film magnetic heads include a method of bonding the cover plates together, a method of bonding the substrate and the cover plate, and the like. The parts 24 and 34 are the thin film layers on which the aforementioned reproducing transducer and recording transducer are formed.
Next, the operation of the conventional thin film magnetic head will be described. First, when the running direction of the magnetic tape is in a normal direction A and the recording format is of four channels, recording is carried out by using the recording transducers 31a, 31b, 31c and 31d of the thin film magnetic head for recording 35, and reproduction is carried out by using the reproducing transducers 21a, 21b, 21c and 21d of the thin film magnetic head for reproducing 25. In case the running direction of the magnetic tape is B and the recording format is of two channels, recording is carried out by using the recording transducers 32a and 32b, and reproduction is carried out by using the reproducing transducers 22a and 22b.
However, in general the tension of the magnetic tape during the tape running is larger in the magnetic head situated on the downstream side of the running direction of the magnetic tape than in the magnetic head situated on the upstream side thereof. Accordingly, the magnetic tape runs in sliding movement in closer contact with the magnetic head on the downstream side. For this reason, it is possible for the magnetic head situated on the downstream side to carry out recording and reproducing in stabilized state in comparison with the magnetic head situated on the upstream side.
However, in the conventional combination type thin film magnetic head, there may be cases where the thin film magnetic head situated on the upstream side is operated in coordination with the running direction of the magnetic tape or recording format or operation mode as to the recording state or reproducing state, etc. In such a case, the sliding condition between the magnetic tape and the thin film magnetic head is aggravated to provide a problem of the impossibility to carrying out stabilized recording and reproducing.